Dynamic resonance system and method for the anti-icing and de-icing of inlet grids

ABSTRACT

In one embodiment, a system includes an inlet grid configured to reduce distortion of an incoming airflow. The system may also include a vibration device coupled to the inlet grid and a controller communicatively coupled to the vibration device. The controller may transmit a vibration signal to the vibration device causing the vibration device to vibrate the inlet grid such that the inlet grid resonates at a natural frequency inducing a mode shape in the inlet grid. The mode shape may break up and prevent ice on the inlet grid.

RELATED APPLICATION

This application is a divisional application of U.S. application Ser.No. 14/833,306 filed Aug. 24, 2015 and entitled “Dynamic ResonanceSystem and Method for Anti-Icing and De-Icing of Inlet Grids.”

TECHNICAL FIELD

This disclosure generally relates to air flow mechanics and, morespecifically, to a dynamic resonance system and method for theanti-icing and de-icing of inlet grids.

BACKGROUND

Air intake systems are engineered to maximize engine efficiency andpower by providing airflow with minimal turbulence and interference. Airintake systems may also provide the necessary airflow for turbines, airconditioning systems, and ventilation systems. A number ofenvironmental, design, and aesthetic considerations may affect theability of an air intake system to provide a sufficient airflow.

SUMMARY OF PARTICULAR EMBODIMENTS

In accordance with the present disclosure, disadvantages and problemsassociated with a dynamic resonance system and method for the anti-icingand de-icing of inlet grids may be reduced or eliminated.

In one embodiment, a system includes an inlet grid configured to reducedistortion of an incoming airflow. The system may also include avibration device coupled to the inlet grid and a controllercommunicatively coupled to the vibration device. The controller maytransmit a vibration signal to the vibration device causing thevibration device to vibrate the inlet grid such that the inlet gridresonates at a natural frequency inducing a mode shape in the inletgrid. The mode shape may break up and prevent ice on the inlet grid.

In one embodiment, a method includes detecting, using a controller, anatmospheric condition sufficient for the accumulation of ice on an inletgrid, the inlet grid configured to reduce the distortion of an airflowpassing through the inlet grid. The method further comprisestransmitting, using the controller, a vibration signal to a vibrationdevice coupled to the inlet grid. The method further comprisesresonating, by the vibration device in response to the vibration signal,the inlet grid at a natural frequency of the inlet grid, therebyinducing a mode shape in the inlet grid. The mode shape may break up andprevent ice on the inlet grid.

Technical advantages of the disclosure include allowing for a largervolume of air to flow through an inlet grid during icing conditions byoptimizing the percentage of the inlet grid covered by the vibrationalexcitation of the anti-icing system. Another technical advantage may bea reduction in the amount of power consumed by the system by operatingat resonant frequencies to produce a simultaneous superposition ofmultiple mode shapes on the inlet grid. Another technical advantage mayinclude preventing structural damage to the anti-icing system byutilizing low-level, dynamic excitation for short bursts of time,thereby reducing mechanical fatigue. Other technical advantages will bereadily apparent to one skilled in the art from the following figures,descriptions, and claims. Moreover, while specific advantages have beenenumerated above, various embodiments may include all, some, or none ofthe enumerated advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of an example dynamic resonancesystem according to certain embodiments;

FIG. 2 illustrates an example block diagram of a dynamic resonancesystem according to certain embodiments; and

FIG. 3 is a flowchart illustrating a dynamic resonance method that maybe utilized by the systems of FIGS. 1 and 2, according to certainembodiments.

DESCRIPTION OF EXAMPLE EMBODIMENTS

To facilitate a better understanding of the present disclosure, thefollowing examples of certain embodiments are given. The followingexamples are not to be read to limit or define the scope of thedisclosure. Embodiments of the present disclosure and its advantages arebest understood by referring to FIGS. 1 through 3, where like numbersare used to indicate like and corresponding parts.

Air intake systems are engineered to maximize engine efficiency andpower by providing airflow with minimal turbulence and interference. Airintake systems may also provide the necessary airflow for turbines, airconditioning systems, and ventilation systems. A number ofenvironmental, design, and aesthetic considerations may affect theability of an air intake system to provide a sufficient airflow.

For example, aircraft occasionally fly through atmospheric conditionsthat lead to the accumulation of ice on certain external aircraftsurfaces and components. A critical component that is susceptible to icebuildup is the engine inlet grid flow straightener. The inlet gridprovides uniform airflow to the engine by reducing air distortion andasymmetric airflows. If the inlet grid accumulates ice, the aerodynamicflow of incoming air may be sufficiently reduced, resulting in reducedengine performance and/or an engine stall.

The accretion of ice on an inlet grid may occur under a number ofscenarios. At certain elevations and temperatures, in-flight icing mayoccur when super cooled water (i.e., rime ice-water in liquid form below0° C.) freezes on impact with the inlet grid. Rime ice typically formson leading edges making inlet grids especially susceptible to iceaccumulation.

To avoid the accumulation of ice on inlet grids, flight plans aremodified to avoid atmospheric icing conditions. However, modified flightplans result in inefficient routes and increased fuel consumption. Othersolutions, such as the use of heating elements to melt accumulated ice,require significant power consumption. Still other remedies, such asmechanical wiper systems, are limited in the inlet grid area that thewiper is able to clear.

To breakup and prevent the accumulation of ice on an inlet grid,embodiments of the present disclosure apply vibrational excitation tothe inlet grid using one or more vibration devices. The one or morevibration devices introduce a dynamic excitation force thatsimultaneously excites one or more natural frequencies and mode shapesof the inlet grid.

A natural or resonant frequency of an inlet grid describes the frequencyat which vibrations in the inlet grid respond at greater amplitude thanat other, non-resonant frequencies. The pattern of vibrational motionsis known as the mode shape. A mode shape may have one or more nodes andanti-nodes. A node of the mode shape experiences little or novibrational displacement, while the mode shape's anti-nodes mayexperience maximum displacement due to the vibrational forces generatedat the natural frequency. A system (e.g., an inlet grid) has an infinitenumber of natural frequencies. Accordingly, a small vibrational forcegenerated by the vibration devices at one or more of the inlet grid'snatural frequencies may produce large vibrational forces at the one ormore anti-nodes of the mode shape.

In some embodiments, the position and excitation direction of the one ormore vibration devices are optimized to maximize the coverage area ofthe inlet grid's mode responses. The resulting multi-frequencyacceleration of the grid may inhibit ice molecules from bonding to thevibrating surface of the inlet grid.

Using one or more vibration devices to apply vibrational excitation toan inlet grid provides several technical advantages not realized bycurrent devices. Embodiments of the present disclosure may allow for alarger volume of air to flow through an inlet grid during icingconditions by optimizing the percentage of the inlet grid covered by thevibrational excitation of the anti-icing system. Another technicaladvantage of the disclosure may be that some embodiments reduce theamount of power consumed by the system by operating at resonantfrequencies to produce a simultaneous superposition of multiple modeshapes on the inlet grid. Yet another advantage may be that someembodiments prevent structural damage of the anti-icing system byutilizing low-level, dynamic excitation for short bursts of time,thereby reducing mechanical fatigue. FIGS. 1-3 provide additionaldetails of a dynamic resonance system and method for the anti-icing andde-icing of inlet grids.

FIG. 1 illustrates a perspective view of an example dynamic resonancesystem 100. System 100 includes inlet grid 110 and vibration devices 120a-n (collectively, vibration devices 120). Vibration devices 120 mayoperate to drive vibrational energy into inlet grid 110, breaking up iceblockages and preventing the further accumulation of ice.

Inlet grid 110 represents any suitable device operable to facilitate theintake of air. In some embodiments, inlet grid 110 acts as an airflowstraightener to minimize the turbulence of the incoming air and providesufficient airflow to an aircraft's engine.

The material of inlet grid 110 may be any suitable material sufficientlyrigid to allow one or more vibration devices 120 to drive vibrationalenergy into inlet grid 110. In some embodiments, the material of inletgrid 110 is dictated by airflow and design requirements of system 100.For example, commercial and residential air conditioning systems may usea metallic material for inlet grid 110 that is durable and long lasting.In some embodiments, inlet grid 110 may be part of a specializedapplication such as jets and helicopters. In these embodiments, inletgrid 110 may be a lighter weight composite or plastic material.

In the illustrated embodiment, inlet grid 110 is shown as a square shapewith square cross-section inlets. However, any suitable cross-sectionshape may be utilized by inlet grid 110, including circular shapes,honeycombs, and hexagonal cells. Similarly, inlet grid 110 may be anyappropriate shape and material depending on the application andenvironment. For example, when inlet grid 110 is utilized on an airplaneor helicopter, inlet grid 110 may be shaped to be aerodynamic andconform with the body of the aircraft as well as handle the requiredairflow levels.

The natural frequencies of inlet grid 110 may change based on the size,shape, length, mass, and material of inlet grid 110. To induce thevibrational energy in inlet grid 110, system 100 may utilize one or morevibration devices 120.

Vibration devices 120 represent any suitable devices that are operableto create mechanical vibration in inlet grid 110. Depending on themagnitude and frequency of the vibrational forces needed, vibrationdevices 120 may include uniform types of vibration devices or acombination of different devices. For example, in some embodiments,vibration devices 120 may include piezoelectric shakers operating athigher frequencies (e.g., 200-2000 Hz). In some embodiments, vibrationdevices 120 may include electromagnetic shakers operating at lowerfrequencies (e.g., 50-1000 Hz). In certain embodiments, vibrationdevices 120 may be integrated to provide a wide frequency range ofoperation.

A number of characteristics and operating parameters of vibrationdevices 120 may be controlled to optimize the coverage area of theinduced mode shapes of inlet grid 110. These parameters include, but arenot limited to, the natural frequencies induced by vibration devices120, the location of vibration devices 120 on inlet grid 110, theexcitation direction of vibration devices 120, the magnitude of thefrequencies generated by vibration devices 120, and the duration of theapplied vibrational force.

In some embodiments, each inlet grid 110 design is tested to determinethe specific natural frequencies and distribution of mode shapes. Byproperly tuning and placing vibration devices 120, the number andduration of operation of vibration devices 120 may be reduced.Optimizing the operating parameters reduces the power consumptionrequired to operate system 100.

In some embodiments, vibration device 120 a produces one or more naturalfrequencies in inlet grid 110. Tuning vibration device 120 a to producea natural frequency may generate a mode shape in inlet grid 110. Themode shape generated by the natural frequency comprises one or morenodes and anti-nodes in inlet grid 110. Vibration device 120 a may thendrive mechanical energy into the anti-nodes of the mode shape toincrease the vibration movement of inlet grid 110 at the anti-nodes. Byproperly tuning and locating anti-nodes in inlet grid 110, the inducedvibrational energy may prevent the accumulation of ice over asignificant portion of inlet grid 110.

For example, vibration device 120 a may be located and operated at afrequency to produce anti-nodes dispersed throughout inlet grid 110.Vibration device 120 a may then drive vibrational energy into theanti-nodes. The magnitude of the excitation energy driven into theanti-nodes may be controlled based on a number of factors such as theenvironmental conditions (e.g., air temperature, engine intakerequirements) and airflow. The vibrational forces at the anti-nodes maythen prevent the accumulation of ice on inlet grid 110.

In some embodiments, vibration devices 120 may have varying excitationdirections. The excitation direction of vibration devices 120 may affectthe displacement direction of anti-nodes in inlet grid 110. Vibrationdevices 120 may be angled to oscillate at any suitable excitationdirection to optimize the vibrational energy driven into inlet grid 110.

For example, vibration device 120 a may oscillate in a first directionto produce transverse waves in inlet grid 110 while vibration device 120b may oscillate in a second direction to produce longitudinal waves ininlet grid 110. Vibration devices 120 may also oscillate at varyingangles with respect to inlet grid 110. For instance, vibration device120 a may be angled at 30 degrees to excite multiple mode shapes ininlet grid 110. In this manner, a single vibration device 120 a maygenerate multiple mode shapes in inlet grid 110.

In some embodiments, each vibration device 120 may operate at adifferent natural frequency of inlet grid 110 to induce different modeshapes. In some embodiments, one or more vibration devices 120 mayoperate at a first natural frequency while one or more additionalvibration devices 120 may operate at different natural frequencies. Themode shapes created by the selected natural frequencies may besuperimposed and/or distributed to provide optimal coverage of inletgrid 110.

Modifications, additions, or omissions may be made to system 100 withoutdeparting from the scope of the disclosure. For example, vibrationdevices 120 may be combined with one or more other anti-icing techniquesto improve the overall performance of system 100. For example, inletgrid 110 may be made of a hydrophobic material or coated with ahydrophobic coating that resists the accumulation of water.

Furthermore, although system 100 is described using inlet grid 110 as apart of an aircraft, system 100 may be applied to any suitableenvironment. For instance, system 100 may be used for other air intakesystems that experience icing conditions such as equipment in freezingweather or ventilation systems in arctic climates (e.g., ocean vesselsand oil platforms). As another example, system 100 may be implemented onair exhaust systems. For instance, system 100 may be implemented on theexhaust screen of a heating, ventilation, and air-conditioning (HVAC)system. In addition to displacing and preventing the build-up of ice,resonating an exhaust screen may prevent and dislodge debris from theoutside of the exhaust screen. Accordingly, system 100 may beimplemented in any suitable situation and environment to prevent theaccumulation of ice, debris, and/or other blockages from accumulating ona screen or grid.

FIG. 2 illustrates an example block diagram 200 of a dynamic resonancesystem 200. System 200 includes controller 210, signal generator 220,and vibration system 230. In the illustrated embodiment, controller 210utilizes signal generator 220 to transmit vibration signal 222 tovibration system 230.

Controller 210 represents any suitable device operable to utilize signalgenerator 220 to tune the vibrational energy generated by vibrationdevices 120. Vibration devices 120 may in turn excite discrete modefrequencies of inlet grid 110 to create steady state vibrational motionat the tuned frequencies. The vibrational motion may inhibit theaccumulation of ice, and/or detach any existing ice on inlet grid 110,thereby maintaining an unobstructed airflow.

Controller 210 may take any suitable physical form. As example and notby way of limitation, controller 210 may be an embedded controller 210,a system-on-chip (SOC), a single-board computer system (SBC) (such as,for example, a computer-on-module (COM) or system-on-module (SOM)), adesktop computer system, a laptop or notebook computer system, a mesh ofcomputer systems, a server, a tablet computer system, or a combinationof two or more of these. Where appropriate, controller 210 may includeone or more controllers 210; be unitary or distributed; span multiplelocations; span multiple machines; or reside in a cloud, which mayinclude one or more cloud components in one or more networks. Whereappropriate, one or more controllers 210 may perform without substantialspatial or temporal limitation one or more steps of one or more methodsdescribed or illustrated herein.

In the illustrated embodiment, controller 210 comprises interface 212,processor 214, and memory 216. Although this disclosure describes andillustrates a particular controller 210 having a particular number ofparticular components in a particular arrangement, this disclosurecontemplates any suitable controller having any suitable number of anysuitable components in any suitable arrangement.

In particular embodiments, interface 212 includes hardware, software, orboth providing one or more interfaces for communication (such as, forexample, packet-based communication) between controller 210, signalgenerator 220 and vibration system 230. As an example and not by way oflimitation, interface 212 may include a network interface controller(NIC) or network adapter for communicating with an Ethernet or otherwire-based network or a wireless NIC (WNIC) or wireless adapter forcommunicating with a wireless network, such as a WI-FI network. Thisdisclosure contemplates any suitable network and any suitable interface212 for it. As an example and not by way of limitation, controller 210may communicate with an ad hoc network, a local area network (LAN), awide area network (WAN), or one or more portions of the Internet or acombination of two or more of these. One or more portions of one or moreof these networks may be wired or wireless. As an example, controller210 may communicate with a wireless PAN (WPAN) (such as, for example, aBLUETOOTH WPAN), a WI-FI network, a WI-MAX network, a cellular telephonenetwork (such as, for example, a Global System for Mobile Communications(GSM) network), or other suitable wireless network or a combination oftwo or more of these. Controller 210 may include any suitable interface212 for any of these networks, where appropriate. Interface 212 mayinclude one or more interfaces 212, where appropriate. Although thisdisclosure describes and illustrates a particular communicationinterface, this disclosure contemplates any suitable interface.

In particular embodiments, processor 214 includes hardware for executinginstructions, such as those making up a computer program. As an exampleand not by way of limitation, to execute instructions, processor 214 mayretrieve (or fetch) the instructions from an internal register, aninternal cache, and/or memory 216; decode and execute them; and thenwrite one or more results to an internal register, an internal cache,and/or memory 216. In particular embodiments, processor 214 may includeone or more internal caches for data, instructions, or addresses. Thisdisclosure contemplates processor 214 including any suitable number ofany suitable internal caches, where appropriate. This disclosurecontemplates processor 214 including any suitable number of any suitableinternal registers, where appropriate. Where appropriate, processor 214may include one or more arithmetic logic units (ALUs); be a multi-coreprocessor; or include one or more processors 214. Although thisdisclosure describes and illustrates a particular processor 214, thisdisclosure contemplates any suitable processor 214.

In particular embodiments, memory 216 includes main memory for storinginstructions for processor 214 to execute or data for processor 214 tooperate on. As an example and not by way of limitation, processor 214may load instructions from memory 216 to an internal register orinternal cache. To execute the instructions, processor 214 may retrievethe instructions from the internal register or internal cache and decodethem. During or after execution of the instructions, processor 214 maywrite one or more results (which may be Intermediate or final results)to the internal register or internal cache. Processor 214 may then writeone or more of those results to memory 216. In particular embodiments,processor 214 executes only instructions in one or more internalregisters or internal caches or in memory 216 and operates only on datain one or more internal registers or internal caches or in memory 216.One or more memory buses (which may each include an address bus and adata bus) may couple processor 214 to memory 216.

In particular embodiments, one or more memory management units (MMUs)reside between processor 214 and memory 216 and facilitate accesses tomemory 216 requested by processor 214. In particular embodiments, memory216 includes random access memory (RAM). This RAM may be volatilememory, where appropriate. Where appropriate, this RAM may be dynamicRAM (DRAM) or static RAM (SRAM). Moreover, where appropriate, this RAMmay be single-ported or multi-ported RAM. In particular embodiments,memory 216 is non-volatile, solid-state memory. In particularembodiments, memory 214 includes read-only memory (ROM). Whereappropriate, this ROM may be mask-programmed ROM, programmable ROM(PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM),electrically alterable ROM (EPROM), or flash memory or a combination oftwo or more of these. This disclosure contemplates any suitable RAM.Memory 216 may include one or more memories 216, where appropriate.Although this disclosure describes and illustrates particular memory,this disclosure contemplates any suitable memory.

Signal generator 220 represents any suitable device operable to produceelectronic signals. Signal generator 220 may generate repeating ornon-repeating signals. Signal generator 220 may produce digital and/oranalog waveforms including, but not limited to, sine waves, saw toothpatterns, pulse signals, square waves, and triangle waves. Signalgenerator 220 may operate in any suitable frequency range (e.g.,1-50,000 Hz).

Controller 210 may utilize signal generator 220 to transmit vibrationsignal 222 to vibration device 120 a. In some embodiments, controller210 transmits a unique vibration signal 222 to each of the one or morevibration devices 120. Vibration device 120 a may then oscillateaccording to vibration signal 222.

For example, controller 210 may utilize signal generator 220 to transmita 100 Hz sine wave to vibration device 120 a using vibration signal 222.Vibration device 120 a may receive vibration signal 222 and oscillate at100 Hz. In some embodiments, 100 Hz is a natural frequency of inlet grid110 and the oscillations of vibration device 120 a induce a mode shapecorresponding to the 100 Hz natural frequency. By resonating inlet grid110 at a natural frequency, a small input magnitude may result in alarge vibrational response preventing the accumulation of ice.

Vibration system 230 includes one or more vibration devices 120 and/orsensors to drive and measure vibrational energy in inlet grid 110. Incertain embodiments, system 200 may include any number of sensorsincluding, but not limited to, accelerometers, vibrational sensors,velocity sensors, and temperature sensors. In embodiments utilizingsensors, the sensors may provide feedback to controller 210 allowingcontroller 210 to dynamically adjust the tuning of vibration devices120. In some embodiments, controller 210 operates as aproportional-integral-derivative (PID) controller receiving feedbackfrom sensors and adjusting the frequency signals of vibration devices120.

In certain embodiments, controller 210 may transmit multiple vibrationsignals 222 to vibration devices 120 to produce one or more resonantfrequencies in inlet grid 110. When the multiple resonant frequenciesare combined with the position and excitation direction of eachvibration device 120, the vibrational response of inlet grid 110 maycreate a simultaneous superposition of multiple mode shapes. Theresulting multi-frequency acceleration of inlet grid 110 may increasethe ability for system 200 to prevent the accumulation of ice on inletgrid 110.

In some embodiments, controller 210 operates as a passive system toprevent the accumulation of ice on inlet grid 110. Controller 210 maystore a list of pre-determined resonant frequencies of inlet grid 110.As explained in FIG. 1, these stored frequencies may be tailored toinlet grid 110 based on the size, shape, weight, and material of inletgrid 110. Controller 210 may then transmit one or more of the storedresonant frequencies to vibration devices 120 to prevent theaccumulation of ice on inlet grid 110. In some embodiments, controller210 transmits a number of the stored resonant frequencies over a periodof time. For example, controller 210 may operate vibration device 120 aat a first stored resonant frequency for a first period of time (e.g.,thirty seconds, a minute, five minutes) and then switch to anotherresonant frequency for a second period of time. In this manner,controller 210 may induce various mode shapes in inlet grid 110 using asingle vibration device 120 a.

In some embodiments, controller 210 operates as an active controllerwith feedback provided by one or more sensors of vibration system 230.Operating as an active system may provide additional technicaladvantages. For example, if inlet grid 110 begins to accumulate ice, themass or stiffness of inlet grid 110 may change. This may affect thenatural frequencies that cause mechanical resonance in inlet grid 110.Using feedback from the sensors (e.g., accelerometers and vibrationalsensors), controller 210 may adjust the frequency of vibration devices120 until a resonant frequency is discovered. As the vibrational energyremoves the accumulated ice from inlet grid 110, controller 210 maycontinue to adjust the frequency transmitted to vibration devices 120 tomaintain the mechanical resonance in inlet grid 110.

To minimize the power consumption of system 100, in some embodiments,controller 210 transmits vibration signal 222 to vibration devices 120in response to detecting the presence of atmospheric conditions thatlead to the accumulation of ice on inlet grid 110. For example,controller 210 may transmit vibration signal 222 to vibration devices120 in response to determining that the air is within a predeterminedtemperature range (e.g., −20° C.-0° C.). Atmospheric conditions may alsoinclude whether an aircraft is traveling through clouds, flying throughprecipitation, or flying above a certain elevation (e.g., 30,000 feet).In some embodiments, controller 210 transmits vibration signal 222 at apredetermined time according to a flight plan or meteorological report.

Controller 210 may transmit vibration signal 222 for any suitable periodof time. For example, controller 210 may transmit vibration signal 222to vibration device 120 a according to a set operating schedule (e.g., 5minutes on, 1 minute off, 5 minutes on). In some embodiments, controller210 may transmit vibration signal 222 while controller 210 detects thepresence of atmospheric conditions that may lead to the accumulation ofice on inlet grid 110.

A component of block diagram 200, such as controller 210, may include aninterface, logic, memory, and other suitable elements. An interfacereceives input, sends output, processes the input and/or output, andperforms other suitable operations. An interface may comprise hardwareand software. Logic performs the operation of the component. Forexample, logic executes instructions to generate output from input.Logic may include hardware, software and other logic. Logic may beencoded in one or more non-transitory, tangible media, such as acomputer readable medium or any other suitable tangible medium, and mayperform operations when executed by a computer. Certain logic, such as aprocessor, may manage the operation of a component. Examples of aprocessor include one or more computers, one or more microprocessors,one or more applications, and other logic.

Modifications, additions, or omissions may be made to system 200 withoutdeparting from the scope of the invention. For example, in someembodiments, controller 210 and signal generator 220 may be integratedin vibration devices 120. As another example, vibration device 120 maybe a hydraulically powered device.

FIG. 3 is a flowchart illustrating an example dynamic resonance method300. At step 310, controller 210 detects the current atmosphericconditions of the air flowing through inlet grid 110. Atmosphericconditions may be any suitable conditions that indicate a likelihoodthat ice may accumulate on inlet grid 110. Atmospheric conditions mayinclude, but are not limited to, temperature readings, precipitationmeasurements, meteorological reports (e.g., cloud types and formations),and elevation.

At step 320, controller 210 determines whether the atmosphericconditions are likely to lead to the accumulation of ice on inlet grid110. If yes, the sequence proceeds to step 330, if no, the sequence mayproceed to step 310 and resume checking the atmospheric conditions. Inthis manner, controller 210 may reduce the power needed to prevent theaccumulation of ice on inlet grid 110 by limiting the operation ofvibration devices 120 to icing conditions.

At step 330, controller 210 transmits vibration signal 222 to at leastone vibration device 120 that is coupled to inlet grid 110. Controller210 may utilize signal generator 220 to select specific frequencies totransmit to vibration devices 120. For example, controller 210 may storea pre-determined number of resonant frequencies tailored to inlet grid110.

At step 340, vibration devices 120 may receive and oscillate at thefrequency according to vibration signal 222. At step 350, controller 210may utilize one or more sensors to determine whether the oscillation ofvibration devices 120 is inducing inlet grid 110 to resonate at anatural frequency. For example, inlet grid 110 may have one or moreaccelerometers or vibrational sensors to determine the amplituderesponse to vibration devices 120 oscillating according to vibrationsignal 222. If inlet grid 110 is not resonating at a natural frequency,the sequence may proceed to step 360. If the sequence is oscillating ata natural frequency, the sequence may proceed to step 370.

At step 360, controller 210 may modify vibration signal 222 transmittedto at least one vibration device 120. By adjusting the frequency atwhich at least one vibration device 120 oscillates, controller 210 maydetermine a natural frequency of inlet grid 110. In some embodiments,the natural frequency of inlet grid 110 may change due to the buildup ofice which may increase the mass or stiffness of inlet grid 110.Controller 210 may continue to adjust vibration signal 222 until anatural frequency of inlet grid 110 is determined.

At step 370, vibration devices 120 continue to oscillate causing inletgrid 110 to resonate at the natural frequency to induce one or more modeshapes in inlet grid 110. The vibrational energy of the mode shapes maythen prevent the accumulation of ice on inlet grid 110.

Controller 210 may continue to transmit vibration signal 222 tovibration devices 120 for any appropriate period of time. For example,controller 210 may transmit vibration signal 222 before entering a cloudcontaining super cooled water, and continue operating until the aircrafthas left the cloud. In some embodiments, inlet grid 110 may be part of aventilation system on a building in an arctic climate. Controller 210may transmit vibration signals 222 while freezing precipitation isfalling.

Various embodiments may perform some, all, or none of the stepsdescribed above. For example, in certain embodiments, controller 210 andvibration devices 120 may be combined to perform each step of method 300from a single device. Furthermore, certain embodiments may perform thesesteps in a different order or in parallel. Moreover, one or more stepsmay be repeated. Any suitable component of system 100 may perform one ormore steps of the method.

The scope of this disclosure encompasses all changes, substitutions,variations, alterations, and modifications to the example embodimentsdescribed or illustrated herein that a person having ordinary skill inthe art would comprehend. The scope of this disclosure is not limited tothe example embodiments described or illustrated herein. Moreover,although this disclosure describes and illustrates respectiveembodiments herein as including particular components, elements,functions, operations, or steps, any of these embodiments may includeany combination or permutation of any of the components, elements,functions, operations, or steps described or illustrated anywhere hereinthat a person having ordinary skill in the art would comprehend.

For example, although FIG. 1 depicts vibration devices 120 a through 120n and example embodiments are illustrated using vibration device 120 a,one or more of the other vibration devices 120 may perform the actionsdescribed using vibration device 120 a while being similar or differentin structure and function. Furthermore, the description of vibrationdevices 120 a through 120 n represents any number of components (from 1through n) and is not necessarily limited to the four depicted vibrationdevices 120.

Furthermore, reference in the appended claims to an apparatus or systemor a component of an apparatus or system being adapted to, arranged to,capable of, configured to, enabled to, operable to, or operative toperform a particular function encompasses that apparatus, system,component, whether or not it or that particular function is activated,turned on, or unlocked, as long as that apparatus, system, or componentis so adapted, arranged, capable, configured, enabled, operable, oroperative.

What is claimed is:
 1. A system, comprising: an inlet grid configured toreduce distortion of an incoming airflow; a vibration device coupled tothe inlet grid; a controller communicatively coupled to the vibrationdevice, the controller configured to transmit a vibration signal to thevibration device; wherein the vibration signal is operable to cause thevibration device to vibrate the inlet grid such that the inlet gridresonates at a natural frequency, thereby inducing a mode shape in theinlet grid, the mode shape configured to break up and prevent ice on theinlet grid; and wherein: the vibration device is a first vibrationdevice, the vibration signal is a first vibration signal, the naturalfrequency is a first natural frequency, and the mode shape is a firstmode shape; and the system further comprises: a second vibration devicecoupled to the inlet grid; the controller is further configured totransmit a second vibration signal to the second vibration device; andthe second vibration signal is operable to cause the second vibrationdevice to vibrate the inlet grid such that the inlet grid resonates at asecond natural frequency, thereby inducing a second mode shape, thesecond mode shape configured to break up and prevent ice on the inletgrid; and the first vibration device and the second vibration deviceoperate concurrently; and the first mode shape and the second mode shapesuperimpose at one or more anti-nodes on the inlet grid.
 2. The systemof claim 1, wherein the first vibration device has a first excitationdirection and the second vibration device has a second excitationdirection.
 3. The system of claim 1, wherein the vibration device is oneselected from the group comprising a piezoelectric shaker and ahydraulically powered shaker.
 4. The system of claim 1, wherein thevibration device comprises an electromagnetic shaker.
 5. The system ofclaim 1, wherein the controller transmits the vibration signal to thevibration device in response to detecting the presence of atmosphericconditions sufficient for ice accumulation on the inlet grid.